[PATCH v4 2/4] btrfs: create structure to encode checksum type and length

[Johannes Thumshirn <jthumshirn@xxxxxxx>]

Create a structure to encode the type and length for the known on-disk
checksums.

This makes it easier to add new checksums later.

Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>

---
Changes to v2:
- Really remove initializer macro *doh*

Changes to v1:
- Remove initializer macro (David)
---
 fs/btrfs/ctree.h | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index d27b39858339..9806135c8310 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -82,9 +82,12 @@ struct btrfs_ref;
  */
 #define BTRFS_LINK_MAX 65535U
 
-/* four bytes for CRC32 */
-static const int btrfs_csum_sizes[] = { 4 };
-static const char *btrfs_csum_names[] = { "crc32c" };
+static const struct btrfs_csums {
+	u16		size;
+	const char	*name;
+} btrfs_csums[] = {
+	[BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
+};
 
 #define BTRFS_EMPTY_DIR_SIZE 0
 
@@ -2207,13 +2210,13 @@ static inline int btrfs_super_csum_size(const struct btrfs_super_block *s)
 	/*
 	 * csum type is validated at mount time
 	 */
-	return btrfs_csum_sizes[t];
+	return btrfs_csums[t].size;
 }
 
 static inline const char *btrfs_super_csum_name(u16 csum_type)
 {
 	/* csum type is validated at mount time */
-	return btrfs_csum_names[csum_type];
+	return btrfs_csums[csum_type].name;
 }
 
 /*
-- 
2.16.4